Dialkyl substituted fatty acids amides are very useful in the commercial-scale production of personal-care formulations, diluents for pesticides and such formulated products.
Several processes for producing different short chain, long chain fatty acids or mixed fatty acids amides or substituted fatty acids amides are known in the prior art. These processes differ from each other with respect to the different process chemistry employed, use of the different basic raw materials, and different experimental parameters.
British patent GB 1,521,997 to Kreidl, et al., discloses that carboxylic acids can be converted with very good yields into the appropriate N,N-disubstituted carboxylic amides when an adduct formed from a disubstituted formamide and a chlorinating agent, such as Thionyl Chloride, is used as the aminating agent.
U.S. pat. No. 3,417,114 to Kuceski discloses method for producing amides by reacting an ester of a carboxylic acid with an amine, using an alkoxide of an alkali metal as catalyst.
U.S. pat. No. 3,674,851 to Senoo, et al., discloses a process for the preparation of aliphatic tertiary amides, which comprises reacting a fatty acid with an alcohol. Additionally a catalyst may be employed to accelerate the rate of reaction. Also disclosed is that all or part of starting materials remaining un-reacted and/or by-products may be recycled to the starting reaction mixture, thereby enabling the yield of the desired aliphatic tertiary amides to be remarkably improved.
U.S. pat. No. 3,751,465 to Takahashi, et al., discloses a novel process for the preparation of N,N-Dialkyl-substituted fatty amides, which comprises reacting at a temperature in the range of 50 to 1000° C. under pressure a nitrile with an alcohol, with or without employing a catalyst, and recycling at least a part of the by-products of the reaction to the starting reaction mixture.
U.S. pat. No. 3,856,791 to Daniher, et al., discloses a novel method for producing amides by contacting phosgene with a mixture of an organic compound containing at least one active hydrogen atom and an acid salt of an amine.
U.S. pat. No. 5,254,684 to Izumi, et al., discloses a process for producing an amide which comprises subjecting an Oxime to liquid phase rearrangement in the presence of phosphorous pentaoxide and at least one compound selected from the group consisting of N,N-Dialkyl amides, N-alkyl cyclic amides and Dialkyl Sulfoxides and optionally a Fluorine containing strong acid or its derivative. The said process can rearrange an Oxime to a corresponding amide in a good yield under mild reaction conditions in the presence of a less stoichiometric amount of a catalyst.
U.S. pat. No. 5,206,225 to Horstmann, et al., discloses the new use of certain alkyl carboxylic acid dimethylamides for prevention of crystallization during the application of aqueous spray liquors based on specific pesticidally active compounds.
Ruhoff, et al., (JACS, Vol. 59, p 401, 1937) reported a process for producing Dimethyl Amides by heating Acetic Acid saturated with gaseous Dimethyl Amine at 35° C. for 5 hrs to 200° C. in a steel bomb, adding Caustic potash to take up water and Acetic Acid and distilling the purified liquid to obtain Dimethyl Amides. Also reported is a process for obtaining Dimethyl Amides in good yields by adding the Acid Chloride in drops during 3 hrs to a concentrated aqueous solution of three moles of Amine kept at −20 to −10° C., saturating the resulting mixture with KOH in the cold and separating and distilling the Dimethyl Amide.
Organic Syntheses Coll. Vol. 4, p. 339, reports a process for producing N, N-Dimethyl Cyclohexane Carboxamide. Thionyl Chloride [179 g] [1.5 m] is added to Cyclohexane Carboxylic Acid during 5 minutes. The mixture is refluxed in an oil bath for 2 hrs and cooled to room temperature (RT). 200 ml of Benzene is charged and the reaction mixture is distilled out till the vapor temperature reaches 95° C. The same operation is repeated with another 200 ml of Benzene. In another flask, a solution of 135 g of Dimethyl Amine [3.0 m] is charged in 150 ml of Anhydrous Benzene and cooled in an ice bath. The Acid Chloride is added to the mixture during 2 hrs and the mixture is stirred overnight. 200 ml of water is added to the mixture and the separated aqueous layer is re-extracted with ether. The combined organic layer is washed with saturated Nacl solution and dried with Magnesium Sulfate. The organic layer is distilled under vacuum to obtain the pure product 138 g [89%].
Textbook of practical Organic Chemistry, by Vogel, 5th Edition, page 708 has reported method of preparation of amides from acid halides. The reaction of acid chloride with an excess of Ammonia represents one of the best procedures for the preparation of amides. The use of primary amines or secondary amines in place of Ammonia yields corresponding secondary or tertiary amides in reaction with acid chlorides. The method of preparation of Hexanamide is also reported. 125 ml of concentrated Ammonia [d-0.88] [25%] [1.96 m] is placed in an ice bath and Hexanoyl Chloride 56 g [0.42 m] is introduced during 2.0 hrs. The solid is filtered and dried to obtain 30 g of Hexanamide [Yield—63%].
Textbook of practical Organic Chemistry, by Vogel, 5th Edition, page 692 has also reported methods of preparation of Hexanoyl Chloride. 58 g [0.5 m] of Hexanoic Acid is heated on a water bath and 72 g [0.6 m] of Thionyl Chloride is added in 45 minutes. The mixture is refluxed for 30 minutes and the Hexanoyl Chloride is isolated by fractional distillation [B.pt.—150-155° C.]. Yield=56 g [83%].
Also reported is the method of preparation of amides from esters. Amides are easily prepared by the interaction of carboxylic esters with concentrated Aqueous Ammonia [Ammonolysis]. The reaction proceeds readily in cold, particularly when the methyl esters of lower molecular weight carboxylic acids are involved, e.g.—Dimethyl Succinate to Succinamide.
Also reported is the method of preparation of amides from Nitriles. Partial hydrolyses of the Nitriles, [for e.g.—Phenyl Acetamide from Benzyl Cyanide] where the nitrile is dissolved in Conc. Hcl at 40° C. would yield amides.
The present invention discloses an alternative route for producing Dialkyl substituted fatty acid amides, which provide a considerably simple process step to obtain the pure form of N,N-Dialkylamides of aliphatic carboxylic acids wherein the carboxylic acid is Hexanoic Acid or Octanoic Acid.